To get certain Firewire/USB external or Internal HD seen by MacOS you need the MassStorage Master Drivers... I ended up having a Copy for the USB/Firewire IBM Externall HD that I linked up to my G4... I have a copy.

These were needed even for MacOS 9.2.2 which I have on the G4... I have not played with them on my 7200, but will try...